To turn from the technique of paper manufacture to a very different cultural feature in order to test the possibility of merging the observed phenomena in the principles of psychology. In several parts of the globe, and most prominently in parts of South America, the aborigines practise a custom known as the ‘couvade’, which forces the father of a new-born child to subject himself to a period of inactive confinement and a series of rigorously observed dietary and other regulations. Let us, for the sake of bringing out the point in high relief, ignore all historical considerations and concentrate exclusively on the subjective elements involved. Whence, then, this strange and wholly irrational association of ideas between fatherhood and a group of taboos? Now the subject of the association of ideas occupies hundreds of pages in psychological literature, yet all this, in itself valuable enough, material has no bearing on our problem, because it is again far too general. We do not doubt for a moment that the association we desire to have illuminated is due either to contiguity or to a perceived similarity of ideas, but why have we this particular association instead of the limitless multitude of associations that would be equally intelligible by the same formulae? Again, many aboriginal tribes of Australia are subdivided into two halves, membership in which is inherited through the father, in some cases, through the mother in others. These moieties are what is technically called ‘exogamous’, _i.e._, marriage with a fellow-member is strictly forbidden. The regulation is, indeed, so stringent, the feeling of horror evoked by a transgression so violent, that in former times offenders were promptly put to death. This sentiment is so strong that even when visiting a remote tribe, perhaps a hundred miles away, where there is no possibility of blood-kinship, an Australian will avoid marriage with a member of the moiety bearing the same name as his own. Here, surely, there is matter for psychology. An Australian has a violent emotional reaction akin to our aversion to incest, and may translate his feelings into the most violent action. Or, looking at the matter from another angle, the Australian exercises an admirable self-control, eschewing on principle marital relations with half the women of his community. Yet all that psychologists tell us of the ethical feelings and the will leaves the problem before us wholly untouched. Why this particular curious feeling developed, what place it occupies in mental life, the psychologist fails to explain. We get, again, simply general formulæ about feeling and will that are equally applicable to the case of a man’s beating his wife or a boy’s resisting the temptations of a lollypop. And this, it must be noted, is dealing with the distinctively psychological aspect of the data. Whether the rule in question originated in a common center and thence spread to